Photographic film



Oct. 19, 1937. s, BABCOCK PHOTOGRAPHIC FILM Original Filed June 19, 19352 Sheets-Sheet 2 Fig; 050

INVENTOR. George S.Babcock BY W E ORNEYS Patented Oct. 19, 1937 UNITEDSTATES PATENT OFFICE- PHOTOGRAPHIO FILM Jersey Application June 19,1935, Serial No. 27,409

Renewed March 30, 1937 1 21 Claims.

This invention relates to photographic materials and more particularlyto photographic film having a high degree of flexibility andsatisfactory emulsion adherence in which an improved type of substratumor undercoat is employed between the light-sensitive emulsion and thefilm support.

In the manufacture of photographic film, especially film of theso-called safety type, in which 1 a light-sensltive emulsion is coatedonto a flexible, relatively uninfiammable cellulose derivative support,two rather serious problems are encountered. One is to get the emulsionto stick properly to the support, and the other is to attain 15 therequisite degree of flexibility. When the adhesion is good, the film asa whole is often brittle and will fracture even with moderate bending.This is probably due to the fact that, since the emulsion adheres soclosely to the support, it is,

go broadly speaking, substantially continuous with it.

zAccordingly, as soon as the emulsion breaks, the energy of impactproduced by the fracture is transmitted directly to the support andcauses it to break also. Experience has shown that when :23 the emulsionadheres less tenaciously to the support, the film is often found to haveunsatisfactory stripping qualities, that is, the emulsion can be liftedor stripped from the base or support too readily to meet therequirements of many photo- 30 graphic uses. It has accordingly alwaysbeen found necessary heretofore to effect some sort of compromisebetween adherence on the one hand and brittleness on the other, and itis well known that one property is invariably gained at 35 the expenseof the other.

As is well known, gelatin emulsions (which are colloidal solutions ordispersions of gelatin in water) cannot be made to adhere directly to acellulose derivative support, because water will not wet this type ofsurface. It is accordingly necessary to apply to the cellulosederivative support a thin layer, substratum, or su as it is generallycalled, of gelatin in order to provide a surface to which the emulsionwill stick. Although a gelatin emulsion, as such, will not adhere to thesupport, a gelatin sub can be made to adhere if it is applied from asubbing solution containing solvents which, not only wet, but su- 0perficially attack, soften, or swell the cellulose derivative materialand thus assist in anchoring the gelatin thereto. Once the gel sub isapplied, it is a relatively simple matter to make the light-sensitiveaqueous emulsion stick to the sup- 55 port, since water will readily wetand soften the surface of the gel coating and the emulsion can thus bemade to adhere to it.

It should be pointed out that when an emulsion is applied to agel-subbed base, the emulsion and gel sub tend to merge and form what,for 5 1 all intents and purposes, may be considered a single continuousgelatin layer on the film, and that the degree of adherence of theemulsion to the support is dependent upon the degree of adherence of thegel sub to the support or to the interve'ning substrata if any. Thisadherence of the gel sub is controlled in practice by controlling the"strength of the gel subbing solution, that is, the solvent or softeningpower of the subbing solution on the cellulose derivative material orintervening substrata. This control of solvent or softening power of thesolution is accomplished by regulating the kind or amount of each of thesolvents used in compounding it. A strong gel subbing solution is,accordingly, one which has a relatively strong solvent, softening orswelling action on the support material and causes the deposited gel subto adhere tenaciously thereto, while a weak subbing solution is onewhich is only weakly solvent with respect to the support material andwill cause the deposited gelatin coating to adhere only slightly. Ingeneral, it may be said that the stronger the gel subbing solution, thegreater will be the degree of adherence of the sub to the support andthe greater 0 the brittleness of the completed film.

The problem of obtaining proper adherence ofthe emulsion without anundue increase in brittleness is a difficult one, especially whendealing with the so-called safety types of films in which the support isformed from a cellulose organic derivative, such as cellulose acetate.When employing cellulose nitrate as the support, it is possible to use arelatively weak gel subbing solution and thus, to a certain extent, tokeep the adherence (and consequently brittleness) down to approximatelythe proper value, but with cellulose organic derivative supports, suchas those formed of cellulose acetate, or cellulose'acetate propionate,for example, much stronger subbing solutions must be employed with theresult that excessive adherence, and therefore excessive brittlenessoccurs. It hasaccordingly been necessary with this latter type ofsupport, first to'apply a thin cellulose nitrate undercoat (which canitself be subbed with relatively weak subbing solutions), and then toapply a gel sub to the ni-- trate surface, followed by the emulsioncoating, but this is disadvantageous because of the fact that itintroduces a certain amount of cellulose nitrate into the finished film,making it difiicult to meet the underwriters specifications for safetyfilm.

A number of expedients have been proposed in the prior art in an attemptto solve this problem of obtaining proper flexibility without an unduesacrifice of emulsion adherence. For example, the use of an undercoat ofrubber or similar cushioning material underneath the emulsion has beensuggested, but it has been found that, similarly to cellulose derivativeundercoats, the impact arising from rupture of the emulsion is transmit1 ted through the rubber layer, causing it to break, and that this breakis carried on into the mate rial of the underlying support. Somewhatsimilar to such products, and suffering many of the same defects, arevarious laminated structures in which bases consisting of celluloseorganic derivatives or other materials have applied thereover a layer orlayers of resinous or rubber-like materials of substantial thickness,these layers constituting a material part of the support and beingapplied, either in the form of separate sheets united to the base byappropriate cement, or deposited, as coatings, from appropriatesolutions.

It is the principal object of the present invention to overcome theabove-mentioned prior art difficulties and to provide a photographicfilm having a high degree of flexibility or freedom from brittleness andat the same time satisfactory emulsion adherence. A further object is toprovide an improved type of safety film .in which flexibility isrendered completely independent of the degree of adherence between theemulsion and the underlying substrata. A specific object is to provide afilm having a colloid-resin mixed sub between the light-sensitivegelatin layer and the film base or support. Other objects will appearhereinafter.

I have found that if the film support is subbed or coated with a thinlayer consisting essentially of a mixture of a colloidal material suchas gelatin and a glyptal resin, subbing solutions of widely varyingstrength may be employed in the subbing operation and the gelatinemulsion may be bound to the mixed gelatin-resin sub or other substrataas tightly as desired without giving rise to brittleness of the finishedphotographic film as a whole. In other words, the use of gelatinglyptalmixed subs renders the matter of fiexibility of such films substantiallyindependent of the degree of adherence existing between the emulsion andthe underlying substrata.

I have also found that a mixed gelatin-glyptal sub may be used alone totake the place of the various substrata heretofore employed, since it iscompatible with and can be made to stick to the cellulose derivativematerial of the film base or support and is of such character that thegelatin emulsion will readily adhere thereto. In some cases it may bedesirable to employ this mixed type of sub in connection with othersubstrata or undercoats as will more fully'appear hereinafter.

I have found that the glyptal resins, when used in accordance with theinvention herein described, are entirely compatible with the material ofthe film base and are also compatible with the photographic emulsion, inthat they do not fog or reduce the sensitivity thereof, or adverselyaffect any of the various processing steps to which the film issubjected during development.

In the accompanying drawings I have illustrated in greatly exaggeratedsection several film acme-rs structures produced in accordance with myinvention and a test by which the flexibility of such films may bedetermined.

Fig. 1 is a section through the body of a completed photographic filmproduced in accordance with my invention and comprising a singlecolloid-resin sub underlying the emulsion.

Fig. 2 is a section through another modification in which a cellulosederivative undercoat has been employed underneath a mixed sub.

Fig. 3 is a section through a modification in which acellulose-derivative-resin mixed layer has been used as an undercoat anda gel sub laid over the undercoat.

' Fig. 4 is a further modification in which a cel-'lulose-derivative-resin mixed undercoat has been employed in connectionwith a gel-resin mixed sub.

Figs. 5 and 6 illustrate the manner of carrying out a brittleness testas described herein.

Figs. 7 and 8 illustrate the behavior of a relatively brittle film whensubjected to the test illustrated in Figs. 5 and 6.

Figs. 9, 10, 11, and 12 illustrate the behavior of films such as shownin Figs. 1, 2, 3, and 4, respectively, when subjected to the brittlenesstest.

In the following examples and description, I have set forth several ofthe preferred embodiments of my invention, but they are included merelyfor purposes of illustration and not as a limitation thereof.

In carrying out my invention, the film base or support, which ispreferably composed of a cellulose organic ester material, such ascellulose acetate or cellulose acetate propionate, is subbed or coatedwith an extremely thin layer of a colloid-resin mixture, such as agelatin-glyptal resin mixture. The resin to be employed in this mixedsub is preferably a glyptal resin (sometimes sold under the trade nameRezyl). These resins are the products formed by reacting a polyhydricalcohol, such as glycerin, with a polybasic acid, such as phthalic acidor its anhydride. A typical method of preparation is described on page293 of the 1923 edition of the text by Carleton Ellis, entitledSynthetic Resins and Plastics, published by the Chemical CatalogCompany. Also included in this category are the alkyd resins, a modifiedtype of glyptal which may be prepared, for example, by reacting apolybasic organic acid with an alcohol having three or more hydroxylgroups in the molecule, a dihydric alcohol, and a dibasic acid. Thenature of these resins is more fully described in an article beginningon page 971 of volume 25 of the Journal of Industrial and EngineeringChemistry, (1933).

The colloidal component of the mixed sub is preferably gelatin, althoughit may. be a cellulose derivative, such as cellulose acetate or similarcolloidal materials which are compatible with the material of the filmbase to which they are applied.

The subbing operation may be carried out by any convenient techniquewell known to those skilled in the art of film making. The material may,for example, be applied from a 3 5% solution of the solid material inappropriate solvents. After drying, the usual light-sensitive. gelatinosilver halide emulsion may be coated directly onto thegelatin-glyptal-subbed surface to which it strongly adheres.

The application of the gelatin-resin mixture to the film support may beaccomplished by any of the subbing operations well known to the art,such as immersion, bead application, or otherwise. The material may besubbed on one or both sides, depending upon the type of film beingproduced. For example, in making X-ray film the emulsion is deposited onboth sides of the support. In producing this type of film in accordancewith my invention the support is subbed on both sides with thegelatin-resin mixture and the emulsion coated on both the subbedsurfaces.

Example 1 In producing a film in accordance with one form of myinvention, a support consisting of a sheet or film of cellulose acetateis led through 'an immersion type hopper containing a solution preparedas indicated below.

A gelatin solution is made up having the following composition:

To 97 parts by weight of this solution are added 3 parts by weight of aglyptal resin, for example, a resin such as that sold under the tradenames Bakelite BR51 or Bakelite BB6? 1.

The support after leaving the subbing apparatus is led through anappropriate drying apparatus maintained at a temperature of 120-200 F.where the solvents are evaporated from the surface of the material, withthe result that a strongly adherent gelatin-resin layer of approximately.00008 inch in thickness is formed. An appropriate gelatino-silverhalide emulsion coating is then applied in the usual manner, thuscompleting the film. A film produced as outlined above is illustrated inFig. 1.

Example 2 Percent Cellulose acetate (69 precipitation value- 29 secondviscosity by the dropping ball method) 2-6 Acetone 7'7 Ethyl alcohol(95%) 21-17 The coated film is then dried at approximately 120 F.producing thereon an extremely thin tightly adhering acetate layer,after which the film is subbed with a gelatin-glyptal resi solution suchas described in Example 1, dried and finally coated with emulsion as inthat example. The resulting product is illustrated in Fig. 2.

I prefer to use a cellulose acetate of low precipitation value (of theorder of 69%) because of. the greater ease of subsequent subbing withgelatin solutions as contrasted, for example, to an acetate ofprecipitation value, although I do not exclude the use of the lattermaterial nor of other types of acetate. The advantage of using the lowerprecipitation value material lies in the fact, which I have discovered,that it is easier to cause a gelatin-containing composition, such as thegelatin-resin mixture herein described or other gelatin subbingcompositions, to adhere to a cellulose acetate surface of 69%'precipitation value, for example, than to one composed of an acetate of90% precipitation value. Although I do not confine myself to anyparticular explanation of this phenomenon, I believe it to be due to thegreater proportion of hydroxyl groups present in the 69% material due tomore extensive hydrolysis, the 69% material containing 3839% acetyl, ascompared to 40-41% acetyl for the 90% material.

Although I can produce a wholly satisfactory product without the use ofthe first (cellulose acetate) layer just described, I have found thatthere is a distinct advantage in doing so, since the thin acetate layerseals in the plasticizer or softener which is always present in the filmbase, and thus prevents its interference with the proper drying down andadherence of the gelatin-resin or other gelatin sub applied thereafter.

Example 3 method) 3.0 Glyptal resin (Bakelite BR51) 1.5 Acetone (orMethyl Cellosolve) 75.5 Ethyl alcohol 20.0

The coated support is dried as in the previous examples, after which itis subbed with a solution, I

of approximately the following composition, per

centages being by weight:

Percent Gelatin 1.2 Acetic acid .12 Water -5.0 Acetone 70.0 Ethylalcohol (95%) 23.68

After appropriate drying the support is then' coated with emuls on,resulting in a product such" as illustrated in Fig. 3.

Example 4 In a still further modification of my invention I may employ aresin as a component of both the cellulose acetate undercoat and thegelatin sub. In accordance with this modification a cellulose acetatesupport, for example, is coated with a cellulose acetate-resincomposition of the type given in Example 3. After drying, the coatedsurface is subbed with a gelatin-resin composition of the type indicatedin Example 1. ing this coating, the emulsion coating is deposited on thesubbed surface as before, the result being illustrated in Fig. 4.

The solvents employed for making up the various subbing solutions willof course be selected upon the basis of the particular resin dealt withand the material of the support or film base to which the solutions areto be applied. Inasmuch as the solvents for these materials are wellwithin the knowledge of those skilled in the art no further explanationin respect to them is considered necessary.

The material of the support may be composed of any suitable celluloseorganic derivative material, such as cellulose acetate, cellulosepropionate, cellulose butyrate, or a mixed cellulose organic ester, suchas cellulose acetate propionate, cellulose acetate butyrate, celluloseacetate stearate, and the like. Although not limited thereto, my

invention relates primarily to the manufacture of the so-called safetytypes of photographic film in which the support is composed of arelatively non-inflammable material, such as the cellulose organicesters, since it is with this type of material that the problem ofbrittleness is most severe. Although in the above examples, I have foundit convenient to illustrate my invention by reference to photographicfilms coated or subbed on one side only, the use of gelatinor othercolloidresin mixed subs as herein described, may be applied with equalsuccess to products, such as portrait film, in which a coating ofgelatin is deposited on the surface opposite the emulsion coating togive greater flatness to the film or X-ray film which is gelandemulsion-coated on both surfaces. It will be apparent that in suchproducts, it is as necessary to prevent brittleness arising from theapplication of the gelatin or other subs on one side of the film as onthe other. I have found that brittleness is as effectively prevented bythe use of the colloid-resin layers in accordance with my invention asin the ease of those films which have layers or coatings on one surfaceonly.

The improvement made possible by my invention will now be made clear bya discussion of the results obtained in carrying out certain tests onthe finished emulsion-coated film. These are the so-called drystripping, wet stripping, and brittleness or flexibility tests.

The dry stripping test is carried out as follows: A piece of thecomplete emulsion-coated film of a convenient size, say, 6 inches wideby 40 inches long, is held at one end with both hands with the emulsionside toward the operator and is then torn lengthwise with successivequick motions of one hand, the tearing generally being carried out at aslight angle to the edge of the strip in order to obtain an obliquetear. The tears thus produced are more or less jagged. An attempt is nowmade to pull back the emulsion coating from the film with thefingernails and the degree to which the emulsion separates from thesupport is a measure of its adherence. It will, of course, be understoodthat the standards of emulsion adherence will vary for different typesof film and what is considered satisfactory for one film may not besatisfactory for another. For example, stripping (emulsion adherence) issaid tobe satisfactory for X-ray film if the emulsion cannot be strippedback more than three or four inches. For Cine film, on the other hand,the stripping should not be greater than about A, of an inch.

The wet stripping test is carried out as follows: A strip of theemulsion-coated film of convenient size is soaked in water at 70 F. forten minutes. It is then removed from the water and fixed on a flatsurface with the emulsion side up. The emulsion is then gouged orcreased with the fingernails at points near the middle and end of thestrip, each nail scratch tearing the emulsion away from the support to acertain extent. The scratched placed are then rubbed with considerableiorce with the balls of the fingertips for several seconds. A film issaid to have satisfactory wet stripping (emulsion adherence) propertieswhen no peeling, or substantially no peeling, of the emulsion occurs asa result of this rubbing action. Wet stripping is said to beunsatisfactory when an appreciable or large amount of the emulsion comesoff. For most types of film it should not be possible to remove pieceswider than inch by this test. I

The test customarily employed for determining the brittleness of X-rayand portrait film is carried out as follows: A strip of film ofconvenient size is heated for forty-five minutes in a brittleness ovenin which air having a controlled rela tive humidity of 20-25% and atemperature of 110-120 F, is circulated. The film is then removed fromthe oven and folded at ten different places along the strip by pressingthe fold suddenly between the forefinger and the thumb. If the film isbrittle, this sudden folding will cause it to break or snap in two atthe fold. The fiexibility maybe defined in terms of freedom frombrittleness which may be figured directly in percentages from theresults of the test. For example, a film is said to be 60% free frombrittleness if it ruptures at only four out of ten folds.

Another test for brittleness customarily applied to Cine film consistsin heating a sample of the film at -100 C. for one hour, after which thefilm is folded between the thumb and finger in several places, with theemulsion side up. If a break occurs all the way across, the film is saidto be brittle. If the break extends only half way across, the film issaid to be slightly brittle, while if the break does not extend morethan a quarter of the way across, the film is said to be very slightlybrittle. If no break occurs, the film is non-brittle.

Referring now to the drawings, in Fig. 1 I have illustrated a sectionthrough a photographic film of the so-called safety type producedsubstantially in accordance with Example 1 above, in which the letter Adesignates a cellulose derivative support composed of cellulose acetate,for example. Superimposed on and tightly adhering thereto is anextremely thin undercoat or substratum B composed of a mixedcolloid-resin sub, such as a mixture of gelatin and a glyptal or alkydresin, this undercoat being approximately .00008 inch in thickness. D isthe final gelatino-silver-halide emulsion layer which adheres tightly tothe mixed sub B.

Fig. 2 represents a film structure prepared substantially as describedin Example 2 and differing from that of Fig. 1, in that the film base Ahas deposited thereon an extremely thin undercoat C of low precipitationvalue cellulose acetate. In this case the mixed gelatin-resin sub B, ofsubstantially the same thickness as the undercoat, is deposited on, andadheres closely to, the undercoat C.

Fig. 3 represents a film structure in which the support or film base Ais first provided with an undercoat F comprising a mixture of celluloseacetate and a resin. In this modification a gelatin sub E of thecustomary type is deposited upon the mixed acetate-resin undercoat F,the emulsion D being applied as in the previous modifications.

In Fig. 4 I have illustrated a still further modification of myinvention in which the film base A is first provided with a mixedcellulose acetateresin undercoat F upon which is deposited the mixedgelatin-resin sub B, followed by the emulsion D.

Figs. 5 and 6 illustrate graphically the manner of carrying out thebrittleness test above referred to. The film A, after removal from thebrittleness oven, is folded at a given place into the form of a shortloop, the gelatin layer D being outermost. This loop is then closed bymeans of the forefinger and thumb, the pressure being applied assuddenly as possible in the direction indicated by the arrows in Fig. 6.

In Figs. 7 and 8, there are illustrated the results obtained when aprior art type of photographic film is subjected to the test illustratedin Figs. 5 and 6. This film comprises a support A, a tightly adheringcellulose derivative undercoat 2: over the support, a gel sub Y over thecellulose derivative undercoat, and an emulsion layer D over the gelsub. It will be seen that the crack starting in the emulsion penetratesthrough the sub layer Y, the undercoat x, and goes on into the materialof the support. This crack almost invariably continues on through thesupport with the result shown in Fig. 8.

Fig. 9 illustrates the results obtained when a film prepared, forexample, as described in Example 1 and employing the colloid-resinundercoats of my invention is subjected to the test illustrated in Figs.5 and 6. Contrary to what would normally be expected, it is found that,notwithstanding the fact that the mixed gelatinresin sub B has beenbound tightly to the film base A and the emulsion D has been likewisetightly bound to the sub 3, the crack starting in the two upper layersis not transmitted through the body of the film base. Correspondingresults are obtained when the film structures of Figs. 2, 3, and 4prepared, respectively, in accordance with Examples 2, 3, and 4 above,are subjected to this same test. While the emulsion and the underlyinglayers may crack when the film is flexed, the rupture in no casepenetrates into the body of the film base. These results strikinglyillustrate the fact that a photographic film produced in accordance withmy invention is characterized by the unusual property of substantially100% freedom from brittleness or, in other words, it has 100%flexibility.

In addition to this remarkable property, films produced in accordancewith my invention respond satisfactorily to both the wet'and drystripping tests above described. In this connection it should be pointedout that one of the outstanding features of my invention is the factthat the adherence of the emulsion may be regulated without regard tothe flexibility of the film. In other words, it is possible to produce afilm in which the emulsion adheres to the support with the highestpracticable degree of tenacity without inducing any brittleness in thefilm as a whole, or causing the support material to break on bending,either during cinematographic or other use, or when subjected to thetests herein described. While I ofler no particular explanation ortheory to account for the unusual and unexpected results obtained inpractice of my invention, it is evident that the mixed colloid-resinsubs or undercoats 'herein described ofier some means of dissipating theimpact on the film base of the rupturing emulsion and underlying layers.This effect is to be distinguished from the mere cushioning efiectcharacteristic of elastic or semielastic materials. In many, althoughnot all cases, the break occurring in the emulsion will penetrate eventhe lowermost undercoat, and these layers may even be released from thesupport to a slight degree, but in no case does the break penetrate thematerial of the support itself.

What I claim is:

1. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic derivative support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening layer comprising an extremely thin subcomposed of a mixture of gelatin and a resin.

2. A photographic film having satisfactory fiexibility and free frombrittleness. comprising a cellulose organic derivative support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening layer comprising an extremely thin subcomposed of a mixture of gelatin and a synthetic resin.

3. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic derivative support and aphotographically sensitive colloid layer adhesively joined'to thesupport by an intervening layer comprising an extremely thin subcomposed of a mixture of gelatin and a polybasic acid-polyhydric alcoholresin.

4. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic derivative support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening layer comprising an extremely thin subcomposed of a mixture of gelatin and an alkyd resin.

5. r A photographic film having satisfactory flexibility and free frombrittleness, comprising. a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by a composite layer comprising an extremely thin cellulosederivative sub adhesively joined to the support and an extremely thinsub composed of a mixture of gelatin and resin adhesively joined to thecellulose derivative sub and to the sensitive colloid layer.

6. A photographic film having satisfactory fiexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by a composite layer comprising an extremely thin cellulosederivative sub adhesively joined to the support and an extremely thinsub composed of a mixture of gelatin and a synthetic resin adhesivelyjoined to the cellulose derivative sub and to the sensitive colloidlayer.

7. A photographic film having satisfactory fiexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by a composite layer comprising an extremely thin cellulosederivative sub adhesively joined to the support and an extremely thinsub composed of a mixture of gelatin and a polybasic acid-polyhydricalcohol resin adhesively joined to the cellulose derivative sub and tothe sensitive colloid layer.

8. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by a composite layer comprising an extremely thin cellulosederivative sub adhesively joined to the support and an extremely thinsub composed of a mixture of gelatin and an alkyd resin adhesivelyjoined to the cellulose derivative sub and to the sensitive colloidlayer.

9. A photographic film having satisfactory fiexibility and free frombrittleness comprising a cellulose acetate support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thincellulose acetate sub adhesively joined to the support and an extremelythin sub composed of a mixture of gelatin and resin adhesively joined tothe cellulose acetate sub and to the sensitive colloid layer.

10. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of a cellulose organic acid ester and a resinadhesively joined to the support and a gel sub adhesively joined to themixed sub and to the sensitive colloid layer.

11. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of a cellulose organic acid ester and asynthetic resin adhesively joined to the support and a gel subadhesively joined to the mixed sub and to the sensitive colloid layer.

12. A photographic fllm having satisfactory flexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of a cellulose organic acid ester and apolybasic acid-polyhydric alcohol resin adhesively joined to the supportand a gel sub adhesively joined to the mixed sub and to the sensitivecolloid layer.

13. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose acetate support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of cellulose acetate and a resin adhesivelyjoined to the support and a gel sub adhesively joined to the mixed suband to the sensitive colloid layer.

14. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose acetate support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of cellulose acetate and a synthetic resinadhesively joined to the support and a gel sub adhesively joined to themixed sub and to the sensitive colloid layer.

15. A photographic film having satisfactory flexibility and free frombrittleness, comprising a fully esterified cellulose acetate support anda photographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer composed of an extremely thinsub composed of a mixture of low precipitation value cellulose acetateand a polybasic acid-polyhydric alcohol resin adhesively joined to thesupport and a gel sub adhesively joined to the mixed sub and to thesensitive colloid layer.

16. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive layer adhesively joined to the support by anintervening layer comprising an extremely thin sub composed of a mixtureof a posed of a mixture of a cellulose organic acid ester and asynthetic resin adhesivelyjoined to the support and an extremely thinsub composed of a mixture of gelatin and a synthetic resin adhesivelyjoined to the first named mixed sub and to the sensitive colloid layer.

18. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose organic acid ester support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of a cellulose organic acid ester and apolybasic acid-polyhydric alcohol resin adhesively joined to the supportand an extremely thin sub composed of a mixture of gelatin and apolybasic acid-polyhydric alcohol resin adhesively joined to the firstnamed mixed sub and to the sensitive colloid layer.

19. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose acetate support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of cellulose acetate and a resin adhesivelyjoined to the support and an extremely thin sub composed of a mixture ofgelatin and a resin adhesively joined to the first named mixed sub andto the sensitive colloid layer.

20. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose acetate support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of cellulose acetate and a synthetic resinadhesively joined to the support and an extremely thin sub composed of amixture of gelatin and a resin adhesively joined to the first namedmixed sub and to the sensitive colloid layer.

. 21. A photographic film having satisfactory flexibility and free frombrittleness, comprising a cellulose acetate support and aphotographically sensitive colloid layer adhesively joined to thesupport by an intervening composite layer comprising an extremely thinsub composed of a mixture of cellulose acetate and a. polybasicacid-polyhydric alcohol resin adhesively joined to the support and anextremely thin sub composed of a mixture of gelatin and a polybasicacid-polyhydric alcohol resin adhesively joined to the first named mixedsub and to the sensitive colloid layer.

GEORGE S. BABCOCK.

